我在尝试启动分布式Tensorflow时遇到了以下错误。我的代码如下所示：

sv = tf.train.Supervisor(is_chief=(task_index == 0), logdir="/tmp/train_logs", init_op=init_op,                         summary_op=summary_op, saver=saver, global_step=global_step, save_model_secs=600)with sv.managed_session(server.target) as sess:step = 0while not sv.should_stop() and step < nnc.steps:    mini_batches = random_mini_batches(x_train, y_train, mini_batch_size)    for mini_batch in mini_batches:        (batch_x, batch_y) = mini_batch        _, step = sess.run([train_op, global_step], feed_dict={x: batch_x, y: batch_y})

当我遇到错误时，它是在random_mini_batches函数上失败的。但我完全不明白这是怎么发生的以及为什么会这样。random_mini_batches函数是用纯Python和numpy编写的，与TensorFlow无关。x_train和y_train之前没有被使用过。

这是我得到的错误信息：

File "/Users/curr_user/PycharmProjects/curr_project/src/nn.py", line 36, in random_mini_batches    num_complete_minibatches = int(math.floor(m / mini_batch_size))  # number of mini batches of size mini_batch_size  File "/Users/curr_user/tensorflow/lib/python2.7/site-packages/tensorflow/python/ops/math_ops.py", line 880, in r_binary_op_wrapper    x = ops.convert_to_tensor(x, dtype=y.dtype.base_dtype, name="x")  File "/Users/curr_user/tensorflow/lib/python2.7/site-packages/tensorflow/python/framework/ops.py", line 611, in convert_to_tensor    as_ref=False)  File "/Users/curr_user/tensorflow/lib/python2.7/site-packages/tensorflow/python/framework/ops.py", line 676, in internal_convert_to_tensor    ret = conversion_func(value, dtype=dtype, name=name, as_ref=as_ref)  File "/Users/curr_user/tensorflow/lib/python2.7/site-packages/tensorflow/python/framework/constant_op.py", line 121, in _constant_tensor_conversion_function    return constant(v, dtype=dtype, name=name)  File "/Users/curr_user/tensorflow/lib/python2.7/site-packages/tensorflow/python/framework/constant_op.py", line 106, in constant    attrs={"value": tensor_value, "dtype": dtype_value}, name=name).outputs[0]  File "/Users/curr_user/tensorflow/lib/python2.7/site-packages/tensorflow/python/framework/ops.py", line 2582, in create_op    self._check_not_finalized()  File "/Users/curr_user/tensorflow/lib/python2.7/site-packages/tensorflow/python/framework/ops.py", line 2290, in _check_not_finalized    raise RuntimeError("Graph is finalized and cannot be modified.")

任何帮助将不胜感激！谢谢

回答：

这不在你的问题中，但我认为mini_batch_size是一个常量张量。尽管random_mini_batches是用纯Python和numpy编写的，TensorFlow重载了许多与张量相关的操作符，因此这一行

num_complete_minibatches = int(math.floor(m / mini_batch_size))

实际上是在对张量执行__div__操作，这会强制将m也转换为张量。但tf.train.Supervisor()会强制图最终确定，即不能再创建节点，因此转换失败了。

解决方案是将mini_batch_size设为普通常量，并确保random_mini_batches内部不使用张量。